Which Old Testament passages does Paul quote regarding Israel’s hardening?

During the time in the wilderness unbelief often prevailed in Israel. At the end of the 40 years of their wandering, Moses observed that the people often failed to be inspired to place their trust in God even despite observing the plagues in Egypt and the miracles in the wilderness (Deuteronomy 29:1–4). Centuries later the prophet Isaiah described that same spiritual blindness among his own contemporaries (Isaiah 29:9–16). Paul summarizes these two comparable passages as follows: As it is written, God gave them a spirit of stupor, eyes that would not see and ears that would not hear, down to this very day (Romans 11:8).

In the same manner, Paul combines a couple of passages from the Psalms which constantly speak about God’s people denying the work of the Lord (Psalm 69:22–23, Psalm 35:8). David there prays that God will not leave them unpunished just because of the fact that they are his chosen nation. Although they are his kinsmen, their actions are unacceptable in the eyes of God. An apostate Israel cannot continue to be Israel: And David says, Let their table become a snare and a trap, a stumbling block and a retribution for them; let their eyes be darkened so that they cannot see, and bend their backs forever (Romans 11:9–10).¹